But overdoing it on activated charcoal could make certain medications less effective. A report in Eater last week said that the efficacy of more than 200 drugs — including the birth control pill — can be hampered by activated charcoal.

"The whole purpose of activated charcoal in the medical world is to prevent absorption of medications or drugs in order to prevent toxicity," Dweck told INSIDER.

Unfortunately, it's not a very specific absorber of substances. "It will absorb anything in your gut, good and bad," Linda Fan, an attending physician in the department of emergency medicine at SUNY Downstate Medical Center, told US News & World Report in 2014.

And charcoal is so good at its job that, in certain circumstances, it really can absorb your birth control's active ingredients before your body gets a chance to. This, of course, can make the pill less effective at preventing pregnancy.

The good news is that small amounts of charcoal aren't likely to cause a problem.

"I'd say if you're eating, like, one ice cream with activated charcoal, you're going to be fine," Dweck said. "But if you're taking in a big [dose], you're going to possibly have a bigger problem."

Dweck recommended leaving at least two hours between your pill and big doses of charcoal, like you might find in supplements or products included in "cleanse" diets.

And remember that this warning applies only to birth control pills you ingest: The effectiveness of the IUD, the implant, the NuvaRing, the shot, and the patch won't be affected by charcoal in the stomach.